Need Advice on Tranny Upgrade

[jaxjeeper]

I'm the proud owner of a 1984 CJ7 , AMC 258 i6 / 4.2l L6. I'm in the process of restoring it. It came with a 4-speed stick (I think it is a T-4 ). I want to upgrade the tranny to a 5-speed. I will probably use the Jeep 70/30 on road/off road. In my readings I see the T-4 and T-5 trannys listed as light duty. I'd like a little more rugged Transmission . Does anyone know of suppliers of Jeep transmissions? I would prefer something that would be a straight swap.

Thanks in advance.

 

[Posi]

T-176 4 speed
Find one with a bell and rear adapter, the T-4 bell is different as is the Transmission cover and rubber boot
DS will be the same

 

[CJim7]

Im afraid you are Limited if you want a 5-speed....especially a straight swap. The only thing even close is the T-5 , but again, it's light duty.

Around the web somewhere, there is information on swapping AX15's into CJ's, but off the top of my head, Im not sure what that entails. The AX15 is a tougher then the T-5 , some circles would call it a medium-duty tranny.

There is the NV4550 and NV3550. These are heavier duty, more expensive, and not even close to a straight swap. But still an option to look into.

 

[ThisGuyUKnow]

This is what that entails

http://www.jeep-cj.com/forums/f2/doing-ax15-yj-booster-swap-4415/

IMO the best 5 speed options are either a nv3550 or ax15

Its a process but doable

 

[Techlight]

From what I've read in general, it was my understanding that the T-4 /T-5 transmissions were fine if you aren't going for a lift and oversize tires and only doing mild wheeling. I would assume this depends on your definition of "restore" in your original post too ...if you're going for stock I'm sure a T-5 would be fine if your looking for a straight swap.

Don't take my word for it though....google around or see what the other people say here. There's not a lack of T-5 weak threads

Funny thing, I just picked up an 84 CJ7 last month with a blown motor...just dumped a new motor in it the other day and looking forward to it running. I'll let you know how my T-5 works out

 

[Neuner]

T-176 4 speed
Find one with a bell and rear adapter, the T-4 bell is different as is the Transmission cover and rubber boot
DS will be the same

New Driveshafts will be needed or existing lengthened/shortened by about 2".

 

[Posi]

New Driveshafts will be needed or existing lengthened/shortened by about 2".

Thanks for the correction, the T-176 is 2.6 shorter so stock DS "could" be lengthened/shortened by 1.3". Depending where the Transmission is mounted there many only be a need to adjust one DS. There are other factors involved as well, length of DS spline, spring and shackle height, road or trail use.

 

[CJim7]

From what I've read in general, it was my understanding that the T-4 /T-5 transmissions were fine if you aren't going for a lift and oversize tires and only doing mild wheeling. I would assume this depends on your definition of "restore" in your original post too ...if you're going for stock I'm sure a T-5 would be fine if your looking for a straight swap.

Don't take my word for it though....google around or see what the other people say here. There's not a lack of T-5 weak threads

Funny thing, I just picked up an 84 CJ7 last month with a blown motor...just dumped a new motor in it the other day and looking forward to it running. I'll let you know how my T-5 works out

The T-4 /T-5 is known to fail during normal driving...even on a stock Jeep. I've been victim to this not once, but twice. Between the cheap (expensive) synchros and the under-sized, over-taxed bearings, these trannys are prone to failure.
I was a fool and rebuilt mine twice.....and they aren't cheap to rebuild. I eventually decided I wasn't going to fall into the "3rd times a charm" crowd and simply replaced it with a nice stout T-18 . Lesson learned.

 

[Petescj]

The T-4 /T-5 is known to fail during normal driving...even on a stock Jeep. I've been victim to this not once, but twice. Between the cheap (expensive) synchros and the under-sized, over-taxed bearings, these trannys are prone to failure.
I was a fool and rebuilt mine twice.....and they aren't cheap to rebuild. I eventually decided I wasn't going to fall into the "3rd times a charm" crowd and simply replaced it with a nice stout T-18 . Lesson learned.

with the voice of reason.

 

[NorthwestCJer]

Nv3500 or ax15. Both came behind 4.0s in tjs Just need to convert to your Transfer Case . Both have decent first gears also.


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[ThisGuyUKnow]

Nv3500 or ax15. Both came behind 4.0s in tjs Just need to convert to your Transfer Case . Both have decent first gears also.


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Not to be a know it all, but that is slightly incorrect information, it is the nv3550 that was in the 4.0s the NV3500 is the chevy light truck version and incompatible as it shares no external dimensions with the 3550.
The Jeep NV3550 Transmission - Novak Conversions

this is the kit for mating the Nv3550 to a Dana 300
50-8604 : Dana 300 Clocking Kit | Advance Adapters

This is the kit for mating an Ax15 to the Dana 300
50-8603 : Jeep Ax15 Adapter Kit to Dana 300 | Advance Adapters

 

[NorthwestCJer]

Yes. 3550. That's what I get for using a phone to write with.


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[Lumpy Grits]

Been run'n a T-5 since I bought my Jeep in 1985.
AMC 258 i6 / 4.2l stock eng & carb. 4:88 R&P, with DL front and rear, 4:1 t'case and 33" BFG/AT tires.
The only reason I ever pulled my T-5 was the front seal started leak'n at 80K miles. Tightened up a few things along with new seals and put it back in.
Got 119K miles on her now. Done all the hard trails and don't baby it.
What kills the T-5 , was the tall gears that AMC used(3:31 or 2:73).
That, and folks using the wrong oil in them. Only use 75W90 syn.
LG

 

[Techlight]

Hey Lumpy...just noticed you're in my area. I grew up in Palmdale and live in Quartz hill. I'll have to hunt you down about 4 wheel clubs in the next few months when I get the CJ on the road.

So after reading tons of posts on the whole "what fluid in the T-5 " I ended up putting syncromesh MTF in my tranny. Maybe I should drain it...How does yours shift? I was worried a bit about that, but I'm more worried about the heat out here with the thinner oil.

 

[Dolf]

For what it’s worth, I had an ’86 for over 20 years. It had the T-5 and 3.31 gears with 31’s. I did lots of old questionable logging roads and sometimes even went off these roads. Never did serious rock crawling or really deep mud, but didn’t have a single problem with the T-5 for over 125K miles.

 

[ThisGuyUKnow]

For what it’s worth, I had an ’86 for over 20 years. It had the T-5 and 3.31 gears with 31’s. I did lots of old questionable logging roads and sometimes even went off these roads. Never did serious rock crawling or really deep mud, but didn’t have a single problem with the T-5 for over 125K miles.

With a T-5 its all about having the correct axle gear for the tire you are using. 2.76 and 31 or larger will most definitely cause your tranny to go boom. The Ax15 and NV3550 are just superior transmissions all around.

 

[Lumpy Grits]

Hey Lumpy...just noticed you're in my area. I grew up in Palmdale and live in Quartz hill. I'll have to hunt you down about 4 wheel clubs in the next few months when I get the CJ on the road.

So after reading tons of posts on the whole "what fluid in the T-5 " I ended up putting syncromesh MTF in my tranny. Maybe I should drain it...How does yours shift? I was worried a bit about that, but I'm more worried about the heat out here with the thinner oil.

Use only syn 75W-90 tranny oil.
I run with the Roughwheelers 4WD Club.
I'm near 10st W. and PMD Blvd.
My daughter lives in QH.
LG

 

[rufus1138]

The T-4 /T-5 is known to fail during normal driving...even on a stock Jeep. I've been victim to this not once, but twice. Between the cheap (expensive) synchros and the under-sized, over-taxed bearings, these trannys are prone to failure.
I was a fool and rebuilt mine twice.....and they aren't cheap to rebuild. I eventually decided I wasn't going to fall into the "3rd times a charm" crowd and simply replaced it with a nice stout T-18 . Lesson learned.

im gonna copy pete with this quote and toss in another vote for the venerable T-18 , compact tough and reliable.